1995-02-01

Driving Product Design Through Early Implementation of 3-D Tolerance Analysis 950858

As a result of increased competition and consumer demands, the automobile's product development cycle is changing and is shorter than ever before in history. The styling features, along with EPA and safety requirements, dictate more complex designs. Manufacturing techniques must be flexible, automated, and capable of higher production rates. Different components, assemblies and major systems are developed and assembled across the world and brought together to produce one vehicle.
It is for the above reasons that dimensional variation in today's automobile design and manufacturing development processes must be understood and managed. The only way to properly accomplish this is to use a tolerance analysis tool with the capabilities to encompass all types of known variations. Understanding and managing these variations early in the product cycle will allow the product team to develop a robust design and manufacturing scheme that considers all dimensional variation.
Focusing on one particular area, the addition of passenger airbags has introduced many dimensional variation related concerns. These concerns directly relate to fit, function, manufacturability, cost, and overall safety performance of the system. Typically many of these concerns go unnoticed until early prototypes are built, measured, and tested. Now, some three dimensional tolerance tools and techniques have the technical capabilities to allow the product team to understand dimensional variation and optimize the product design and manufacturing before problems occur in prototype and production
VSA-3D is one of the 3-D tolerance analysis tools available that has been used to evaluate Instrument Panel designs and flag potential problem areas prior to any tooling dollars being spent. This paper will focus on the area of Passenger Air Bag Doors and how the early implementation of the Dimensional Management Process, specifically, 3-Dimensional tolerance analysis, can save costly tooling rework, improve quality, and increase safety. Some of the typical causes of excessive assembly variation are; 1) Component design, 2) Component tolerances, 3) Assembly methods, 4) Assembly locating schemes, and 5) Assembly sequence. By modifying any one or combination of these you can reduce the variation seen in the final assembly. Early 3-Dimensional tolerance analysis can evaluate the impact of modifying any one or combination of the above without excessive tooling dollars being spent.

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